<form method="POST" action="#">
    <table>
        <tr>
            <td>Username</td>
            <td><input name="username"></td>
        </tr>
        <tr>
            <td>Password</td>
            <td><input type="password" name="password"></td>
        </tr>
    </table>
<button type="submit" name="login">Login</button>
</form>
<?php echo $error_message?>